1. Field of the Invention
The present invention relates to passive electronic devices and particularly to multilayer flexible circuits characterized by high capacitance. Specifically, the present invention is directed to flexible circuits having ceramic capacitors embedded therein and, in some applications, also including inductors connected to the capacitors.
2. Description of the Prior Art
Flexible circuits are well known and have been widely used. A typical multilayer flexible circuit will be comprised of at least two non-conductive plastic sheets having conductive circuit patterns supported on at least one planar surface of each sheet. These sheets will customarily be positioned so that the circuit patterns face each other, but are not in electrical contact. Electrical isolation between the conductors patterns on the two sheets will usually be accomplished by spatially separating the sheets through the use of an intermediate nonconductive layer. This intermediate layer may either be a further plastic sheet, adhesively bonded to the circuit supporting sheets, or a nonconductive binder.
Prior flexible circuits have a capacitance which is so low as to be comparatively ineffective in any frequency sensitive circuit, such as a filter or network, noise.
In order to overcome this disadvantageous low capacitance, discrete capacitors were often inserted into terminal holes in the circuit and soldered into place. This required additional assembly time and expense. Furthermore, the solder connections were subject to environmental degradation, and are typically points of higher resistance in the circuit.